Selection and characterization of human immunodeficiency virus type 1 variants resistant to the (+) and (-) enantiomers of 2'-deoxy-3'-oxa-4'-thio-5-fluorocytidine

Antimicrob Agents Chemother. 2000 May;44(5):1127-31. doi: 10.1128/AAC.44.5.1127-1131.2000.


Human immunodeficiency virus (HIV) type 1 (HIV-1) variants were selected for resistance to the (+) and (-) enantiomers of a novel nucleoside analogue, 2'-deoxy-3'-oxa-4'-thio-5-fluorocytidine (dOTFC), by use of the infectious molecular clone HIV HXB2D and the human T-cell line MT-4. The dOTFC-resistant variants that were selected were 10-fold less sensitive than wild-type virus, and cloning and sequencing of the complete reverse transcriptase (RT)-coding region identified the mutation M184V. Studies with mutated recombinant HXB2D virus confirmed the importance of the M184V mutation in conferring resistance to (-)dOTFC in MT-4 cells, although no difference in sensitivity was observed in primary cells. The M184V substitution also displayed decreased susceptibility to (+)dOTFC. Selection with (+)dOTFC also produced variants which were 10-fold more resistant than the wild type, and a novel mutation, D67G, was identified following cloning and sequencing of the RT genes. The D67G mutation was introduced into HXB2D by site-directed mutagenesis, and the data obtained confirmed the importance of this mutation in conferring resistance to both (+)dOTFC and (-)dOTFC. Mutated recombinant molecular clone HXB2D-D67G was further selected with (+)dOTFC, and three of six clones sequenced contained both the D67G and M184V mutations, while the other three of the six clones contained only the D67G mutation. Clinical isolates of HIV-1 which are (-) 2'-deoxy-3'-thiacytidine-resistant also displayed resistance to both (+)dOTFC and (-)dOTFC.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-HIV Agents / pharmacology*
  • Deoxycytidine / analogs & derivatives*
  • Deoxycytidine / pharmacology
  • Drug Resistance, Microbial
  • HIV-1 / drug effects*
  • HIV-1 / genetics
  • HIV-1 / isolation & purification
  • HIV-1 / metabolism
  • Humans
  • Microbial Sensitivity Tests
  • Mutation
  • Structure-Activity Relationship
  • Thionucleosides / pharmacology*


  • 2'-deoxy-3'-oxa-thiocytidine
  • Anti-HIV Agents
  • Thionucleosides
  • Deoxycytidine
  • 2'-deoxy-5-fluoro-3'-thiacytidine